CancerNetwork® spoke with Dr. Peter Schmid about the KEYNOTE-522 trial.
We spoke with Peter Schmid, MD, PhD, at the European Society for Medical Oncology Congress 2019, held in Barcelona, Spain from September 27, 2019 to October 1, 2019. Dr. Schmid shared some of the background behind the KEYNOTE-522 trial.
Triple-negative breast cancer is a more aggressive subtype compared to other subtypes of breast cancer. It often affects younger women. The standard treatment for triple-negative breast cancer is chemotherapy. Most patients with triple-negative breast cancer in the early disease settings will have surgery and chemotherapy and increasingly, we give chemotherapy before surgery in the form of neoadjuvant therapy.
What we try to see with neoadjuvant therapy is that the cancer completely disappears at the time of surgery which is what we describe as a [pathological complete response rate]. If you use an anthracycline-taxane combination, the achievement is about 40%. If you add in platinum, the achievement is about 50% to 52%. Now this is important, because large analyses have demonstrated that patients who achieve a PCR have a fantastic outlook and the recurrence risk is very low. Ninety to 95% of patients will not see any recurrence in that situation. However, patients who do not experience a PCR, we find residual tumor at the surgery. Even if we remove that residual tumor, unfortunately they have a relatively high risk of recurrence. Often around 40% to 50% in the first 3 to 5 years.
So, if we increase to the PCR rates and hopefully increase long term recurrence, we reduce the long term recurrence risk and also improve the cure rates. The KEYNOTE-522 trial is the first neoadjuvant trial of immune therapy in this setting and it combined the immune checkpoint inhibitor pembrolizumab (Keytruda) with standard chemotherapy before surgery. Patients receive 6 months of chemotherapy with either pembrolizumab or placebo. Then patients underwent surgery and after surgery, patients received another 6 months of pembrolizumab alone or placebo alone.